The Multiple Integrated Laser Engagement System (MILES) employs a suite of detectors on each target. The target may be an individual or a vehicle. The Individual Weapon Systems (IWS) include a vest employing 8 detectors, and a headband employing 4 detectors. The vehicle systems use one or more belts employing up to 8 detectors in each. In both cases the requirement is that the suite of detectors covers 360 degrees in azimuth.
The transmitted laser energy is kept as low as possible to minimize the eye-damage hazard. Because of this, the detectors need to be as sensitive as possible, within limits set by cost, size, weight, complexity, and downward compatibility in sensitivity.
Most of the MILES detectors in use today have evolved little since the inception of the MILES program several decades ago. These detectors employ a silicon active element behind a slightly-curved plastic cover, with an electromagnetic interference (EMI) filter interposed between the active element and the cover. The detector assembly is hermetically sealed to exclude the environment.
The silicon active element is specified to be 1+/−0.2 square centimeters in area. These detector assemblies are about 1⅝ inches in diameter and ⅝ inches high. They are hermetically sealed in a relatively heavy metal can having a glass window.
Because of the detector geometry and the optical properties of the cover, the field of view of the detectors is limited. Typical coverage in elevation is on the order of 60 degrees from a line normal to the detector. Detector sensitivity falls to 50 percent at 45 degrees from the normal. This means that at least four detectors are required on the headband to have 360 degrees of coverage with equal sensitivity in all azimuthal directions.
For the vest, four detectors in a square array are on the front of the individual, and another four detectors are on the individual's back, leaving azimuthal zones of 90 degrees on the right and left sides of the individual where the sensitivity falls to zero directly right and left.
There is thus an on-going need for detectors which can provide better coverage to thereby address above noted problems of known detectors. Preferably improved coverage could be achieved while at the same time reducing the total number of detectors that is needed.